Answer:
A. 30.7cm
B. 
C. The electric field is directed away from the point of charge
Explanation:
A.

B.
Considering Gauss's law

C. The electric field directed away from the point of charge when the charge is positive.
Answer:
Work Done = 67.5 J
Explanation:
First we find the value of spring constant (k) using Hooke's Law. Hooke's is formulated as:
F = kx
where,
F = Force Applied = 450 N
k = Spring Constant = ?
x = Stretched Length = 30 cm = 0.3 m
Therefore,
450 N = k(0.3 m)
k = 450 N/0.3 m
k = 1500 N/m
Now, the formula for the work done in stretching the spring is given as:
W = (1/2)kx²
Where,
W = Work done = ?
k = 1500 N/m
x = 70 cm - 40 cm = 0.3 m
Therefore,
W = (1/2)(1500 N/m)(0.3 m)²
<u>W = 67.5 J</u>
The acceleration of gravity on Earth is 9.8 m/s². That means that
an object falling under the influence of gravity will move 9.8 m/s
faster than it was moving a second earlier.
Falling from rest, it will be moving 9.8 m/s after the first second,
and 19.6 m/s after the 2nd second.
The height from which it fell doesn't matter.
C. Upper mantle is further supdivided near the surface of two zones: - Asthenosphere - mean density about 3.3 g/cc. Denser and hotter than lithosphere above.
Answer:
414.9 m
Explanation:
First, become familiar with the horizontal, and vertical vector components.
Vertical vector: Vy = V × sin (θ).
Horizontal vector: Vx = V × cos(θ).
Distance traveled = Velocity vector × time in the air.
Time in the air given Vy = 2 × Vy / g (in respect to the metric of the vector).
Range of the projectile = Vx² / g
Time in the air given Vx = (Vx + √(Vx)² + 2gh) / g.
Given a 28° angle with an initial velocity of 70m/s, we have enough information to calculate!
Vx = 70 m/s × cos(28°) ≈ 61.806 m/s
Vy = 70 m/s × sin(28°) ≈ 32.863 m/s
t = 2 × Vy / g
t = 2 × ≈32.863 / 9.8
t = ≈65.726 / 9.8
t ≈ 6.7 s
Distance traveled (horizontal) = Vx × t = 61.806 × 6.7 ≈ 414.9 m